Method to control a hybrid powertrain, vehicle comprising such a hybrid powertrain, computer program for controlling such a hybrid powertrain, and a computer program product comprising program code

ABSTRACT

Provided is a method to control a hybrid powertrain to achieve a reverse drive, wherein the hybrid powertrain comprises an internal combustion engine; a gearbox with an input and output shaft; a first planetary gear connected to the input shaft and a first main shaft; a second planetary gear connected to the first planetary gear and a second main shaft; first and second electrical machines respectively connected to the first and second planetary gears; one gear pair connected with the first main shaft and the output shaft; and one gear pair connected with the second main shaft and the output shaft, wherein the internal combustion engine is connected with the first planetary gear via the input shaft. The method comprises: ensuring that moveable component parts in the first planetary gear are disconnected from each other and/or that moveable component parts in the second planetary gear are disconnected from each other; ensuring that an output shaft in the internal combustion engine is prevented from rotating; and controlling the first electrical machine and/or second electrical machine to achieve a negative torque in the output shaft via the first main shaft and/or second main shaft.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a national stage application (filed under 35 §U.S.C.371) of PCT/SE2015/051021, filed Sep. 29, 2015 of the same title, which,in turn claims priority to Swedish Application No. 1451147-1 filed Sep.29, 2014 of the same title; the contents of each of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a method to control a hybrid powertrainin a vehicle.

BACKGROUND OF THE INVENTION

Hybrid vehicles may be driven by a primary engine, which may be aninternal combustion engine, and a secondary engine, which may be anelectrical machine. The electrical machine is equipped with at least oneenergy storage device, such as an electro-chemical energy storagedevice, for storage of electric power, and control equipment to controlthe flow of electric power between the energy storage device and theelectrical machine. The electrical machine may thus alternately operateas an engine and as a generator, depending on the vehicle's operatingmode. When the vehicle is braked, the electrical machine generateselectric power, which is stored in the energy storage device. This isusually referred to as regenerative braking, which entails that thevehicle is decelerated with the help of the electrical machine and theinternal combustion engine. The stored electric power is used later foroperation of the vehicle.

A gearbox in a hybrid vehicle may comprise a planetary gear. Theplanetary gear usually comprises three components, which are rotatablyarranged in relation to each other, namely a sun wheel, a planetarywheel carrier and an internal ring gear. With knowledge about the numberof teeth in the sun wheel and the ring gear, the mutual rotationalspeeds of the three components may be determined during operation. Oneof the components of the planetary gear may be connected with an outputshaft in an internal combustion engine. This component of the planetarygear thus rotates with a rotational speed corresponding to therotational speed of the output shaft in the internal combustion engine.A second component in the planetary gear may be connected with an inputshaft to a transmission device. This component of the planetary gearthus rotates with the same rotational speed as the input shaft to thetransmission device. A third component in the planetary gear is used toachieve hybrid operation, connected with a rotor in an electricalmachine. This component in the planetary gear thus rotates with the samerotational speed as the rotor of the electrical machine, if they aredirectly connected with each other. Alternatively, the electricalmachine may be connected with the third component of the planetary gearvia a transmission that has a gearing. In this case, the electricalmachine and the third component in the planetary gear may rotate withdifferent rotational speeds. The engine speed and/or the torque of theelectrical machine may be controlled steplessly. During operating modeswhen the input shaft to the transmission device must be provided with arotational engine speed and/or torque, a control device having knowledgeabout the engine speed of the internal combustion engine calculates therotational speed with which the third component must be operated, inorder for the input shaft to the transmission device to obtain thedesired rotational speed. A control device activates the electricalmachine in such a manner that it provides the third component with thecalculated engine speed, and thus the input shaft to the transmissiondevice with the desired rotational speed.

By connecting the internal combustion engine's output shaft, theelectrical machine's rotor and the transmission device's input shaftwith a planetary gear, the conventional clutch mechanism may be avoided.At acceleration of the vehicle, an increased torque must be deliveredfrom the internal combustion engine and the electrical machine to thetransmission device, and further to the vehicle's driving wheels. Sinceboth the internal combustion engine and the electrical machine areconnected with the planetary gear, the largest possible torque deliveredby the internal combustion engine and the electrical machine will belimited by one of these drive units; i.e. the one whose maximum torqueis lower than the other drive unit's maximum torque, having regard tothe gearing between them. In case the electrical machine's highesttorque is lower than the internal combustion engine's highest torque,having regard to the gearing between them, the electrical machine willnot be able to generate a sufficiently large reaction torque to theplanetary gear, entailing that the internal combustion engine may nottransfer its highest torque to the transmission device and further tothe vehicle's driving wheels. Thus, the highest torque that may betransferred to the transmission device is limited by the electricalmachine's strength. This is also apparent from the so-called planetequation.

Using a conventional clutch, which disconnects the gearbox's input shaftfrom the internal combustion engine during shifting processes in thegearbox, entails disadvantages, such as heating of the clutch discs,resulting in wear of the clutch discs and an increased fuel consumption.A conventional clutch mechanism is also relatively heavy and costly. Italso occupies a relatively large space in the vehicle.

In a vehicle, the space available for the drive arrangement is oftenlimited. If the drive arrangement comprises several components, such asan internal combustion engine, an electrical machine, a gearbox and aplanetary gear, the construction must be compact. If there areadditional components, such as a regenerative braking device, therequirements that the component parts must have a compact constructionare even more stringent. At the same time, the component parts in thedrive arrangement must be designed with dimensions that are able toabsorb the required forces and torque.

For some types of vehicles, especially heavy goods vehicles and buses, alarge number of gear steps is required. Thus, the number of componentparts in the gearbox increases, which must also be dimensioned to beable to absorb large forces and torque arising in such heavy goodsvehicles. This results in an increase of the size and weight of thegearbox.

There are also requirements for high reliability and high operationalsecurity of the components comprised in the drive device. In case thegearbox comprises multi-plate clutches, a wear arises, which impacts thereliability and life of the gearbox.

At regenerative braking, kinetic energy is converted into electricpower, which is stored in an energy storage device, such asaccumulators. One factor impacting on the life of the energy storagedevice is the number of cycles in which the energy storage deviceprovides and extracts power to and from the electrical machines. Themore cycles, the shorter the life of the energy storage device.

Under some operating conditions, it is desirable to shut off theinternal combustion engine, with the objective of saving fuel and toavoid cooling down of the internal combustion engine's exhaust treatmentsystem. When a torque addition is required in the hybrid powertrain, orwhen the energy storage device must be charged, the internal combustionengine must be started quickly and efficiently.

The document EP-B1-1126987 shows a gearbox with double planetary gears.The sun wheel of each planetary gear is connected to an electricalmachine, and the internal ring gears of the planetary gears areconnected with each other. The planetary wheel carrier in each planetarygear is connected to a number of gear pairs, so that an infinite numberof gear steps is obtained. Another document, EP-B1-1280677, also showshow the planetary gears may be bridged with a gear step arranged on theinternal combustion engine's output shaft.

Document US-A1-20050227803 shows a vehicle transmission with twoelectrical machines, connected to the respective sun wheels in twoplanetary gears. The planetary gears have a common planetary wheelcarrier, which is connected to the transmission's input shaft.

The document WO2008/046185-A1 shows a hybrid transmission with twoplanetary gears, wherein one electrical machine is connected to one ofthe planetary gears and a double clutch interacts with the secondplanetary gear. Both planetary gears also interact with each other via acogwheel transmission.

SUMMARY OF THE INVENTION

Despite prior art solutions in the field, there is a need to furtherdevelop a method to control a hybrid powertrain, in order to achieve anegative torque in the output shaft in an advantageous manner.

The objective of the present invention is accordingly to provide a noveland advantageous method to control a hybrid powertrain.

Another objective of the invention is to achieve a negative torque inthe output shaft in an advantageous manner.

Another objective of the invention is to provide a novel andadvantageous computer program to control a hybrid powertrain.

The method according to the invention provides an efficient and reliablemethod to control a hybrid powertrain in order to achieve reverse drive,comprising an internal combustion engine; a gearbox with an input shaftand an output shaft; a first planetary gear, connected to the inputshaft and a first main shaft; a second planetary gear, connected to thefirst planetary gear and a second main shaft; a first electricalmachine, connected to the first planetary gear; a second electricalmachine, connected to the second planetary gear; at least one gear pair,connected with the first planetary gear and the output shaft; and atleast one gear pair, connected with the second planetary gear and theoutput shaft, wherein the internal combustion engine is connected withthe first planetary gear via the input shaft. The method suitablycomprises the step of ensuring that the moveable parts of the firstplanetary gear are disconnected from each other and/or that the moveableparts of the second planetary gear are disconnected from each other. Themethod also comprises the steps of ensuring that an output shaft in theinternal combustion engine is prevented from rotating, and ofcontrolling the first electrical machine and/or the second electricalmachine, in such a manner that a negative torque is achieved in theoutput shaft via the first main shaft and/or the second main shaft. Thenegative torque in the output shaft acts to achieve a negativerotational speed direction in the output shaft. A negative rotationalspeed direction in the output shaft entails, when the hybrid powertrainis arranged in a vehicle, that the output shaft rotates in a directionwhich is opposite to the rotational speed direction when the vehicle isdriven in a forward direction. In this manner, the vehicle may bereversed, without the need to engage a special reverse gear.

The fact that the moveable component parts in the first planetary gearare disconnected from each other suitably entails that a first sun wheeland a first planetary wheel carrier, both arranged in the firstplanetary gear, are disconnected from each other. Similarly, the factthat the moveable component parts comprised in the second planetary gearare disconnected from each other suitably entails that a second sunwheel and a second planetary wheel carrier, both arranged in the secondplanetary gear, are disconnected from each other. The fact that themoveable parts of each respective planetary gear are disconnected fromeach other is defined as the moveable parts not being locked to eachother.

According to one aspect of the invention, the method comprises first adecision, as to whether the first electrical machine and/or the secondelectrical machine should be controlled in order to achieve a negativetorque in the output shaft. Subsequently the movable parts in the firstplanetary gear are disconnected in such cases, where the firstelectrical machine will be controlled in order to achieve a negativetorque in the output shaft, and the moveable parts are thus disconnectedin the second planetary gear in such cases, where the second electricalmachine will be controlled in order to achieve a negative torque in theoutput shaft.

A first and second clutch device is arranged between the planetary wheelcarrier and the sun wheel of the respective planetary gears. The task ofthe clutch devices is to lock the respective planetary wheel carrierswith the sun wheel. When the planetary wheel carrier and the sun wheelare connected with each other, the power from the internal combustionengine will pass through the planetary wheel carrier, the clutch device,the sun wheel and further along to the gearbox, which entails that theplanetary wheels do not absorb any torque. This entails that thedimension of the planetary wheels may be adapted only to the electricalmachine's torque, instead of to the internal combustion engine's torque,which in turn means the planetary wheels may be designed with smallerdimensions. Thus, a drive arrangement according to the invention isobtained, which has a compact construction, a low weight and a lowmanufacturing cost.

In order to release a planetary gear's planetary wheel carrier and sunwheel from each other, the first and/or second electrical machine iscontrolled, in such a way that torque balance is achieved in theplanetary gear. Torque balance relates to a state where a torque acts ona ring gear arranged in the planetary gear, representing the product ofthe torque acting on the planetary wheel carrier of the planetary gearand the gear ratio of the planetary gear, while simultaneously a torqueacts on the planetary gear's sun wheel, representing the product of thetorque acting on the planetary wheel carrier and (1−the planetary gear'sgear ratio). In the event two of the planetary gear's component parts,i.e. the sun wheel, the internal ring gear or planetary wheel carrier,are connected with the use of a clutch device, this clutch device doesnot transfer any torque between the planetary gear's parts when torquebalance prevails. Accordingly, the clutch device may easily be shiftedand the planetary gear's component parts may be disconnected.

The clutch devices and the locking mechanisms preferably comprise anannular sleeve, which is shifted axially between a connected and adisconnected state. The sleeve encloses, substantially concentrically,the gearbox's rotating components and is moved between the connected anddisconnected state with a power element. Thus, a compact construction isobtained, with a low weight and a low manufacturing cost.

The output shaft of the internal combustion engine is connected with thefirst planetary wheel carrier, arranged in the first planetary gear, andthe step of preventing rotation of the output shaft suitably comprisesensuring that a locking device is locked, so that the planetary wheelcarrier is locked to the gear house of the gearbox. If the internalcombustion engine rotates when the method described herein is initiated,the internal combustion engine and/or the first electrical machineand/or the second electrical machine is suitably controlled in such amanner that the internal combustion engine's output shaft issubstantially at a standstill, before the locking device is locked. Bylocking the internal combustion engine's output shaft and the firstplanetary wheel carrier with the gearbox's housing with the use of thelocking device, the gearbox, and thus the vehicle, becomes adapted forelectric drive by the electrical machines. The electrical machines thusemit a torque to the output shaft of the gearbox. Alternatively, thestep of preventing rotation of the output shaft of the internalcombustion engine comprises that a braking element, arranged inconnection with the output shaft, is controlled in such a way that theoutput shaft of the internal combustion engine is decelerated to astandstill.

The electrical machines, which are connected to the planetary gears, maygenerate power and/or supply torque depending on the desired operatingmode. The electrical machines may also, in certain operating modes,supply each other with power.

The first planetary gear is connected with the first main shaft, and thesecond planetary gear is connected with the second main shaft. The firstplanetary wheel carrier in the first planetary gear is connected withthe second sun wheel of the second planetary gear. The first sun wheelin the first planetary gear is connected with the first main shaft, andthe second planetary wheel carrier in the second planetary gear isconnected with the second main shaft. Thus, a transmission is obtained,which shifts gears without torque interruption.

The gearbox is preferably equipped with a number of gear pairs arrangedbetween the first main shaft and a countershaft, and between the secondmain shaft and the countershaft, respectively. These gear pairs areconnected to the output shaft via the countershaft. The gear pairspreferably comprise cogwheels, which may be mechanically locked to anddisconnected from the countershaft. Thus, a number of fixed gear stepsare obtained, which may be shifted without torque interruption. Thecogwheels that may be locked on the countershaft also result in acompact construction with high reliability and high operationalsecurity. Alternatively, pinion gears in the gear pairs may be arrangedto be lockable with and disconnectable from the first or second mainshaft.

Suitably, the at least one gear pair connected with the first main shaftcomprises a pinion gear and a cogwheel in engagement with each other,which first pinion gear is fixedly arranged with the first main shaft,and which first cogwheel is connectable and disconnectable arranged on acountershaft.

Suitably, the at least one gear pair connected with the second mainshaft comprises a pinion gear and a cogwheel in engagement with eachother, which pinion gear is fixedly arranged with the second main shaft,and which second cogwheel is connectable and disconnectable arranged onthe countershaft.

Each of the gear pairs has a gearing, which is adapted to the vehicle'sdesired driving characteristics. The gear pair with the highest gearing,in relation to the other gear pairs, is suitably connected when thelowest gear is engaged.

With the gearbox according to the invention conventional slip clutchesbetween the internal combustion engine and the gearbox may be avoided.

According to one aspect of the present invention the negative torque isachieved in the output shaft by way of—before the disconnection of thefirst and/or the second planetary gear's moveable parts—ensuring that apath for torque transmission via the gearbox has been established.Preferably, the method comprises—before the disconnection of the firstand/or the second planetary gear's moveable parts—ensuring that theoutput shaft is connected with the first and/or the second electricalmachine. In this manner, torque transmission from the first and/or thesecond electrical machine to the output shaft is facilitated.

According to one aspect of the present invention, the negative torque inthe output shaft is achieved by way of—before the disconnection of thefirst and/or the second planetary gear's moveable parts—ensuring thatthe main shaft connected with the first planetary gear and the outputshaft are connected with the use of a clutch mechanism. In this manner,a direct gear is achieved, whereat the first electrical machine mayachieve a negative torque in the output shaft without any connected gearpair. Preferably the connection of the first main shaft with the outputshaft is achieved by way of achieving a synchronous rotational speedbetween the first main shaft and the output shaft, whereat the clutchmechanism is shifted, so that it connects the first main shaft and theoutput shaft.

According to one aspect of the present invention, the negative torque inthe output shaft is achieved by way of—before the disconnection of themoveable parts of the first and/or the second planetary gear—ensuringthat the at least one gear pair connected with the first main shaft isconnected to the countershaft, and that a fifth gear pair connected withthe output shaft is connected with the countershaft.

Preferably, the step comprises controlling the first electrical machineand/or the second electrical machine in such a manner that a negativetorque is achieved in the output shaft, controlling the first electricalmachine, in order to achieve a rotation of the first electrical machinein a first direction, whereat the output shaft is made to rotate in anopposite, second direction. The first direction is a positive direction.Suitably, the first electrical machine is controlled in such a way thatit emits a positive torque, so that a rotation of the first electricalmachine in the first direction is achieved. The positive torque from thefirst electrical machine acts on the first sun wheel, and thus on thefirst main shaft, so that they may rotate in a second direction,opposite to the first direction. That is to say, the positive torquefrom the first electrical machine results in the first sun wheel, andthus the first main shaft, being able to obtain a negative rotationalspeed direction. In such cases where the first main shaft and the outputshaft are connected via a clutch mechanism, the output shaft thusobtains the same negative rotational speed direction as the first mainshaft. In such cases where a gear pair connected with the firstplanetary gear is connected to the countershaft, and where the fifthgear pair connected to the output shaft is connected to thecountershaft, a negative rotational speed direction of the first mainshaft entails that the countershaft will obtain a positive rotationalspeed direction. Since the countershaft is connected with the outputshaft via the fifth gear pair, a positive rotational speed direction inthe countershaft will entail that the output shaft obtains a negativerotational speed direction. By controlling the first electrical machinein such a way that it generates a positive torque, a negative rotationalspeed direction is thus achieved in the output shaft in a flexiblemanner.

According to one aspect of the present invention, the method comprisesthe additional step—before the disconnection of the first and/or thesecond planetary gear's moveable part —, of ensuring that the at leastone gear pair connected with the second main shaft is connected to thecountershaft, and that the fifth gear pair connected with the outputshaft is connected to the countershaft.

Preferably the step comprises controlling the first electrical machineand/or the second electrical machine in such a manner that a negativetorque is achieved in the output shaft, controlling the secondelectrical machine in order to achieve a rotation of the secondelectrical machine in a second direction, wherein the output shaft ismade to rotate in the same, second direction. The second direction is anegative direction. Suitably, the second electrical machine iscontrolled in such a way that it emits a negative torque, so that therotation of the second electrical machine in the second direction isachieved. The negative torque from the second electrical machine acts onthe second planetary wheel carrier, and thus on a second main shaftconnected with the second planetary wheel carrier, so that they mayrotate in the same, second direction. That is to say, the result of thenegative torque from the second electrical machine is that the secondplanetary wheel carrier and the second main shaft may obtain a negativerotational speed direction. By connecting a gear pair connected with thesecond planetary gear with the countershaft, the countershaft obtains arotational speed direction that is opposite to the second main shaft.When the second electrical machine is controlled in order to achieve anegative torque in the output shaft, and this results in the second mainshaft obtaining a negative rotational speed direction, the countershaftobtains a positive rotational speed direction. Since the countershaft isconnected with the output shaft via the fifth gear pair, a positiverotational speed direction in the countershaft will entail that theoutput shaft may obtain a negative rotational speed direction.

The negative torque in the output shaft may thus be transferred from therespective first and the second electrical machine, via the first mainshaft and/or the second main shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Below is a description, as an example, of preferred embodiments of theinvention with reference to the enclosed drawings, on which:

FIG. 1 schematically shows a side view of a vehicle with hybridpowertrain, arranged to be controlled according to the method, accordingto the present invention,

FIG. 2 shows a schematic side view of a hybrid powertrain, arranged tobe controlled according to the method, according to the presentinvention, and

FIG. 3a-3c shows flow charts relating to methods to control a hybridpowertrain according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic side view of a vehicle 1, comprising a gearbox2 and an internal combustion engine 4, which are comprised in a hybridpowertrain 3. The internal combustion engine 4 is connected to thegearbox 2, and the gearbox 2 is further connected to the driving wheels6 of the vehicle 1 via a propeller shaft 9. The driving wheels 6 areequipped with brake devices 7 to brake the vehicle 1.

FIG. 2 shows a schematic side view of a hybrid powertrain 3 with agearbox 2, comprising an input shaft 8, a first and a second planetarygear 10 and 12, respectively, a first and a second electrical machine 14and 16, respectively, a countershaft 18 and an output shaft 20. Thehybrid powertrain 3 comprises an internal combustion engine 4 connectedto the gearbox 2. The internal combustion engine 4 is connected with thegearbox 2 via the input shaft 8 of the gearbox. The internal combustionengine has an output shaft 97. The output shaft 97 of the internalcombustion engine 4 is connected to the input shaft of the gearbox 2.The first planetary gear 10 has a first internal ring gear 22, to whicha first rotor 24 in the first electrical machine 14 is connected. Thefirst planetary gear 10 also has a first sun wheel 26 and a firstplanetary wheel carrier 50. The first planetary gear 10 is connected toa first main shaft 34. The first main shaft 34 is connected with thefirst sun wheel 26, arranged in the first planetary gear 10. The secondplanetary gear 12 has a second internal ring gear 28, to which a secondrotor 30 of the second electrical machine 16 is connected. The secondplanetary gear 12 has a second sun wheel 32 and a second planetary wheelcarrier 51. The second planetary gear 12 is connected to a second mainshaft 36. The first and the second sun wheels 26 and 32, respectively,are coaxially arranged, which, according to the embodiment displayed,entails that a first main shaft 34 arranged on the first sun wheel 26extends inside a second main shaft 36, which is arranged on the secondplanetary wheel carrier 51 and equipped with a central bore 38. It isalso possible to arrange the first main shaft 34 in parallel with andnext to the second main shaft 36. In this case, the countershaft 18 issuitably arranged between the first main shaft 34 and the second mainshaft 36, and the torque may be extracted directly from the countershaft18. The countershaft 18 thus constitutes, in this case, the output shaft20.

The internal combustion engine 4 is connected with the first planetarywheel carrier 50, and the first planetary wheel carrier 50 is connectedwith the second sun wheel 32.

The first electrical machine 14 is equipped with a first stator 40,which is connected to the vehicle 1, via a gear housing 42 surroundingthe gearbox 2. The second electrical machine 16 is equipped with asecond stator 44, which is connected to the vehicle 1, via a gearhousing 42 surrounding the gearbox 2. The first and the secondelectrical machine 16 are connected to an energy storage device 46, suchas a battery, which, depending on the vehicle's 1 operating mode,operates the electrical machines 14 and 16. At other operating modes,the electrical machines 14 and 16, respectively, may work as generators,whereat power is supplied to the energy storage device 46. An electroniccontrol device 48 is connected to the energy storage device 46 andcontrols the supply of power to the electrical machines 14 and 16.Preferably the energy storage device 46 is connected to the electricalmachines 14 and 16, respectively, via a switch 49, which is connected tothe control device 48. In some operating modes, the electrical machines14 and 16, respectively, may also operate each other. Electric power isthen led from one of the electrical machines 14, 16 to the secondelectrical machine 14, 16 via the switch 49, connected to the electricalmachines 14, 16. Thus, it is possible to achieve a power balance betweenthe electrical machines 14, 16. Another computer 53 may also beconnected to the control device 48 and the gearbox 2.

The first planetary gear 10 is equipped with a first planetary wheelcarrier 50, on which a first set of planetary wheels 52 is mounted. Thesecond planetary gear 12 is equipped with a second planetary wheelcarrier 51, on which a second set of planetary wheels 54 is mounted. Thesecond main shaft 36 is connected with the second planetary wheelcarrier 51, arranged in the second planetary gear 12. The first set ofplanetary wheels 52 interacts with the first internal ring gear 22 andthe first sun wheel 26. The second set of planetary wheels 54 interactswith the second internal ring gear 28 and the second sun wheel 32. Theinput shaft 8 of the gearbox 2 is connected with the first planetarywheel carrier 50.

A first clutch device 56 is arranged between the first sun wheel 26 andthe first planetary wheel carrier 50. By arranging the first clutchdevice 56 in such a way that the first sun wheel 26 and the firstplanetary wheel carrier 50 are connected with each other, and maytherefore not rotate in relation to each other, the first planetarywheel carrier 50 and the first sun wheel 26 will rotate with equalrotational speeds.

A second clutch device 58 is arranged between the second sun wheel 32and the second planetary wheel carrier 51. By arranging the secondclutch device 58 in such a way that the second sun wheel 32 and thesecond planetary wheel carrier 51 are connected with each other, and maytherefore not rotate in relation to each other, the second planetarywheel carrier 51 and the first sun wheel 32 will rotate with equalrotational speeds.

Preferably, the first and second clutch devices 56, 58 comprise a firstand a second splines-equipped clutch sleeve 55 and 57, respectively,which is axially shiftable on a splines-equipped section on the firstand second, respectively, planetary wheel carrier 50 and 51, and on asplines-equipped section on the respective sun wheels 26 and 32. Byshifting the respective clutch sleeve 55, 57 in such a manner that thesplines-equipped sections are connected via the respective clutchsleeves 55, 57, the first planetary wheel carrier 50 and the first sunwheel 26, as well as the second planetary wheel carrier 51 and thesecond sun wheel 32, respectively, become mutually interlocked with eachother and may not rotate in relation to each other.

The first and second clutch device 56, 58, according to the embodimentdisplayed in FIG. 2, are arranged between the first sun wheel 26 and thefirst planetary wheel carrier 50, and between the second sun wheel 28and the second planetary wheel carrier 51, respectively.

However, it is possible to arrange an additional or alternative clutchdevice (not displayed) between the first internal ring gear 22 and thefirst planetary wheel carrier 50, and also to arrange an additional oralternative clutch device (not displayed) between the second internalring gear 28 and the second planetary wheel carrier 51.

A transmission device 19, which comprises a first gear pair 60, arrangedbetween the first planetary gear 10 and the output shaft 20 is connectedto the first and the second main shaft 34, 36. The first gear pair 60comprises a first pinion gear 62 and a first cogwheel 64, which are inengagement with each other. A second gear pair 66 is arranged betweenthe second planetary gear 12 and the output shaft 20. The second gearpair 66 comprises a second pinion gear 68 and a second cogwheel 70,which are in engagement with each other. A third gear pair 72 isarranged between the first planetary gear 10 and the output shaft 20.The third gear pair 72 comprises a third pinion gear 74 and a thirdcogwheel 76, which are in engagement with each other. A fourth gear pair78 is arranged between the second planetary gear 12 and the output shaft20. The fourth gear pair 78 comprises a fourth pinion gear 80 and afourth cogwheel 82, which are in engagement with each other.

On the first main shaft 34, the first and the third pinion gears 62 and74, respectively, are arranged. The first and the third pinion gears 62and 74, respectively, are fixedly connected with the first main shaft34, so that they may not rotate in relation to the first main shaft 34.On the second main shaft 36, the second and the fourth pinion gears 68and 80, respectively, are arranged. The second and the fourth piniongears 68 and 80, respectively, are fixedly connected with the secondmain shaft 36, so that they may not rotate in relation to the secondmain shaft 36.

The countershaft 18 extends substantially in parallel with the first andthe second main shaft 34 and 36, respectively. On the countershaft 18,the first, second, third and fourth cogwheels 64, 70, 76 and 82,respectively, are mounted. The first pinion gear 62 engages with thefirst cogwheel 64, the second pinion gear 68 engages with the secondcogwheel 70, the third pinion gear 74 engages with the third cogwheel 76and the fourth pinion gear 80 engages with the fourth cogwheel 82.

The first, second, third and fourth cogwheels 64, 70, 76 and 82,respectively, may be individually locked with and released from thecountershaft 18 with the assistance of the first, second, third andfourth clutch elements 84, 86, 88 and 90, respectively. The clutchelements 84, 86, 88 and 90, respectively, preferably consist ofsplines-equipped sections on the cogwheels 64, 70, 76 and 82,respectively, and on the countershaft 18, which interact with the fifthand sixth clutch sleeves 83, 85, which engage mechanically with thesplines-equipped sections of the respective first to fourth cogwheel 64,70, 76 and 82 and of the countershaft 18. The first and third clutchelements 84, 88 are preferably equipped with a common clutch sleeve 83,and the second and fourth clutch elements 86, 90 are preferably equippedwith a common clutch sleeve 85. In the released state, a relativerotation may occur between the respective cogwheels 64, 70, 76 and 82and the countershaft 18. The clutch elements 84, 86, 88 and 90,respectively, may also consist of friction clutches. On the countershaft18 a fifth cogwheel 92 is also arranged, which engages with a sixthcogwheel 94, which is arranged on the output shaft 20 of the gearbox 2.

The countershaft 18 is arranged between the respective first and secondplanetary gears 10, 12 and the output shaft 20, so that the countershaft18 is connected with the output shaft 20 via a fifth gear pair 21, whichcomprises the fifth and the sixth cogwheel 92, 94. The fifth cogwheel 92is connectable and disconnectable arranged on the countershaft 18 withthe use of a fifth clutch element 93.

By disconnecting the fifth cogwheel 92, which is arranged to bedisconnectable from the countershaft 18, it is possible to transfertorque from the second planetary gear 12 to the countershaft 18 via, forexample, the second gear pair 66, and to further transfer torque fromthe countershaft 18 to the output shaft 20 via, for example, the firstgear pair 60. Thus, a number of gear steps is obtained, wherein torquefrom one of the planetary gears 10, 12 may be transferred to thecountershaft 18, and further along from the countershaft 18 to the mainshaft 34, 36 connected with the second planetary gear 10, 12, in orderto finally transfer torque to the output shaft 20 of the gearbox 2. Thispresumes, however, that a clutch mechanism 96, arranged between thefirst main shaft 34 and the output shaft 20, is connected, which isdescribed in more detail below.

The fifth cogwheel 92 may be locked to and released from thecountershaft 18 with the assistance of a fifth clutch element 93. Theclutch element 93 preferably consists of splines-equipped sectionsadapted on the fifth cogwheel 92 and the countershaft 18, which sectionsinteract with a ninth clutch sleeve 87, which engages mechanically withthe splines-equipped sections of the fifth cogwheel 92 and thecountershaft 18. In the released state, a relative rotation may occurbetween the fifth cogwheel 92 and the countershaft 18. The fifth clutchelement 93 may also consist of friction clutches.

Torque transfer from the input shaft 8 of the gearbox 2 to the outputshaft 20 of the gearbox 2 may occur via the first or the secondplanetary gear 10 and 12, respectively, and the countershaft 18. Thetorque transfer may also occur directly via the first planetary gear 10,whose first sun wheel 26 is connected, via the first main shaft 34, tothe output shaft 20 of the gearbox 2 via a clutch mechanism 96. Theclutch mechanism 96 preferably comprises a splines-equipped seventhclutch sleeve 100, which is axially shiftable on the first main shaft 34and on the splines-equipped sections of the output shaft 20. By shiftingthe seventh clutch sleeve 100, in such a way that the splines-equippedsections are connected via the seventh clutch sleeve 100, the first mainshaft 34 becomes locked with the output shaft 20, which, when rotating,will therefore have the same rotational speed. By disconnecting thefifth cogwheel 92 of the fifth gear pair 21 from the countershaft 18,torque from the second planetary gear 12 may be transferred to thecountershaft 18, and further along from the countershaft 18 to the firstmain shaft 34, connected with the first planetary gear 10, in order tofinally transfer torque via the clutch mechanism 96 to the output shaft20 of the gearbox 2.

During operation, the gearbox 2 may in some operating modes operate insuch a manner that one of the sun wheels 26 and 32, respectively, islocked with the first and the second planetary wheel carrier 50 and 51,respectively, with the help of the first and the second clutch device 56and 58, respectively. The first and the second main shaft 34 and 36,respectively, then obtain the same rotational speed as the input shaft 8of the gearbox 2, depending on which sun wheel 26 and 32, respectively,is locked with the respective planetary wheel carriers 50 and 51. One orboth of the electrical machines 14 and 16, respectively, may operate asa generator to generate electric power to the energy storage device 46.Alternatively, the electrical machine 14 and 16, respectively, mayprovide a torque addition, in order to thus increase the torque in theoutput shaft 20. In some operating modes, the electrical machines 14 and16, respectively, will supply each other with electric power,independently of the energy storage device 46.

It is also possible that both the first and the second electricalmachine 14 and 16, respectively, simultaneously generate power to theenergy storage device 46. At engine braking the driver releases theaccelerator pedal (not displayed) of the vehicle 1. The output shaft 20of the gearbox 2 then operates one or both electrical machines 14 and16, respectively, while the internal combustion engine 4 and theelectrical machines 14 and 16, respectively, engine brake. In this case,the electrical machines 14 and 16, respectively, generate electricpower, which is stored in the energy storage device 46 in the vehicle 1.This operating state is referred to as regenerative braking. In order tofacilitate a more powerful braking effect the output shaft 97 of theinternal combustion engine 4 may be locked, and thus be prevented fromrotating. Thus, only one of or both the electrical machines 14 and 16,respectively, will function as a brake and generate electric power,which is stored in the energy storage device 46. The locking of theoutput shaft 97 of the internal combustion engine 4 may also be carriedout when the vehicle has to be accelerated by only one or both theelectrical machines 14 and 16. If the torque of one or both of therespective electrical machines 14 and 16 overcomes the torque off theinternal combustion engine 4, and having regard to the gearing betweenthem, the internal combustion engine 4 will not be able to resist thelarge torque generated by the respective electrical machines 14 and 16,so that it becomes necessary to lock the output shaft 97 of the internalcombustion engine 4. Locking of the output shaft 97 of the internalcombustion engine 4 may also be necessary when the vehicle 1 is reversedwith the first electrical machine 14 and/or the second electricalmachine 16. The locking of the output shaft 97 of the internalcombustion engine 4 is preferably carried out with a locking device 102,which is arranged between the first planetary wheel carrier 50 and thegear housing 42. By locking the first planetary wheel carrier 50 and thegear housing 42, the output shaft 97 of the internal combustion engine 4will also be locked, since the output shaft 97 of the internalcombustion engines 4 is connected with the first planetary wheel carrier50 via the input shaft 8 of the gearbox. The locking device 102preferably comprises a splines-equipped eighth clutch sleeve 104, whichis axially shiftable on a splines-equipped section of the firstplanetary wheel carrier 50, and on a splines-equipped section of thegear housing. By shifting the eight clutch sleeve 104 in such a mannerthat the splines-equipped sections are connected via the clutch sleeve104, the first planetary wheel carrier 50, and therefore the outputshaft 97 of the internal combustion engine 4, is prevented fromrotating.

The control device 48 is connected to the electrical machines 14 and 16,respectively, in order to control the respective electrical machines 14and 16 in such a way that they, during certain applicable operatingmodes, use stored electric power to supply driving power to the outputshaft 20 of the gearbox 2, and during other operating modes use thekinetic energy of the output shaft 20 of the gearbox 2 to extract andstore electric power. The control device 48 thus detects the rotationalspeed and/or the torque of the output shaft 97 of the internalcombustion engine 4 via sensors 98 arranged at the electrical machines14 and 16, respectively, and in the output shaft 20 of the gearbox 2, inorder thus to gather information and to control the electrical machines14 and 16, respectively, to operate either as electrical motors orgenerators. The control device 48 may be a computer with softwaresuitable for this purpose. The control device 48 also controls the flowof power between the energy storage device 46 and the respective stators40 and 44 of the electrical machines 14 and 16, respectively. At suchtimes when the electrical machines 14 and 16, respectively, operate asengines, stored electric power is supplied from the energy storagedevice 46 to the respective stators 40 and 44. At such times when theelectrical machines 14 and 16 operate as generators, electric power issupplied from the respective stators 40 and 44 to the energy storagedevice 46. However, as stated above, the electrical machines 14 and 16,respectively, may, during certain operating modes, supply each otherwith electric power, independently of the energy storage device 46.

The first and the second clutch devices 56 and 58, respectively, thefirst, second, third, fourth and fifth clutch elements 84, 86, 88, 90and 93, respectively, the clutch mechanism 96 between the first mainshaft 34 and the output shaft 20, and the locking device 102 between thefirst planetary wheel carrier 50 and the gear housing 42, are connectedto the control device 48 via their respective clutch sleeves. Thesecomponents are preferably activated and deactivated by electric signalsfrom the control device 48. The clutch sleeves are preferably shifted bynon-displayed power elements, such as hydraulically or pneumaticallyoperated cylinders. It is also possible to shift the clutch sleeves withelectrically powered power elements.

The example embodiment in FIG. 2 shows four pinion gears 62, 68, 74 and80, respectively, and four cogwheels 64, 70, 76 and 82, respectively, aswell as two respective planetary gears 10 and 12, with associatedelectrical machines 14 and 16. However, it is possible to adapt thegearbox 2 with more or fewer pinion gears and cogwheels, and with moreplanetary gears with associated electrical machines.

Below, an up-shift from a first to a seventh gear will be described,wherein the gearbox 2 is arranged in a vehicle 1. All seven gears entailforward drive of the vehicle.

The input shaft 8 of the gearbox 2 is connected to the output shaft 97of the vehicle's 1 internal combustion engine 4. The output shaft 20 ofthe gearbox 2 is connected to a driving shaft 99 in the vehicle 1. Atidling of the internal combustion engine 4 and when the vehicle 1 is ata standstill, the input shaft 8 of the gearbox 2 rotates at the sametime as the output shaft 20 of the gearbox 2 is at a standstill. Thelocking device 102 is deactivated, so that the output shaft 97 of theinternal combustion engine 4 may rotate freely. Since the input shaft 8of the gearbox 2 rotates, the first planetary wheel carrier 50 will alsorotate, which entails that the first set of planetary wheels 52 willrotate. Since the first planetary wheel carrier 50 is connected to thesecond sun wheel 32, the second sun wheel 32, and thus also the secondset of planetary wheels 54, will rotate. By not supplying power to thefirst and the second electrical machines 14 and 16, respectively, therespective first and the second internal ring gears 22 and 28, which areconnected with the respective first and second rotor 24 and 30 of theelectrical machines 14 and 16, respectively, will rotate freely, so thatno torque is absorbed by the respective internal ring gears 22 and 28.The respective first and the second clutch devices 56 and 58 aredisconnected and thus not actuated. Thus, no torque will be transferredfrom the internal combustion engine 4 to the sun wheel 26 of the firstplanetary gear 10, or to the planetary wheel carrier 51 of the secondplanetary gear 12. The clutch mechanism 96 between the first main shaft34 and the output shaft 20 is disconnected, so that the first main shaft34 and the output shaft 20 may rotate freely in relation to each other.Since the first planetary gear's sun wheel 26, the planetary wheelcarrier 51 of the second planetary gear 12 and the output shaft 20 ofthe gearbox 2 are, at this stage, at a standstill, the countershaft 18is also at a standstill. In a first step the fourth cogwheel 82 and thethird cogwheel 76 are connected with the countershaft 18 with theassistance of the fourth and third clutch elements 90 and 88,respectively. The first cogwheel 64 and the second cogwheel 70 aredisconnected from the countershaft 18. Thus, the first cogwheel 64 andthe second cogwheel 70 are allowed to rotate freely in relation to thecountershaft 18. The fifth cogwheel 92 of the fifth gear pair 21 islocked on the countershaft 18 with the assistance of the fifth clutchelement 93.

In order to start the rotation of the output shaft 20 of the gearbox 2,with the objective of driving the vehicle 1, the fourth pinion gear 80and the fourth cogwheel 82 on the countershaft 18 must be brought torotate. This is achieved by making the second planetary wheel carrier 51rotate. When the second planetary wheel carrier 51 rotates, the secondmain shaft 36 will also rotate, and thus the fourth pinion gear 80,which is arranged on the second main shaft 36, also rotates. The secondplanetary wheel carrier 51 is made to rotate by controlling the secondinternal ring gear 28 with the second electrical machine 16. Byactivating the second electrical machine 16 and controlling the internalcombustion engine 4 towards a suitable engine speed, the vehicle 1begins to move as the second main shaft 36 begins to rotate. When thesecond planetary wheel carrier 51 and the second sun wheel 32 achievethe same rotational speed, the second sun wheel 32 is locked with thesecond planetary wheel carrier 51, with the assistance of the secondclutch device 58. As mentioned above, the second clutch device 58 ispreferably adapted in such a way that the second sun wheel 32 and thesecond planetary wheel carrier 51 engage mechanically with each other.Alternatively, the second clutch device 58 may be adapted as a slipbrake or a multi-plate clutch which connects, in a smooth way, thesecond sun wheel 32 with the second planetary wheel carrier 51. When thesecond sun wheel 32 is connected with the second planetary wheel carrier51, the second planetary wheel carrier 51 will rotate with the samerotational speed as the output shaft 97 of the internal combustionengine 4. Thus, the torque generated by the internal combustion engine 4is transferred to the output shaft 20 of the gearbox 2 via the fourthpinion gear 80, the fourth cogwheel 82 on the countershaft 18, the fifthcogwheel 92 on the countershaft 18, and the sixth cogwheel 94 on theoutput shaft 20 of the gearbox 2. The vehicle 1 will thus begin to moveoff and be propelled by a first gear.

Each of the first, second, third and fourth gear pairs 60, 66, 72, 78has a gearing, which is adapted to desired driving characteristics ofthe vehicle 1. According to the example embodiment displayed in FIG. 2,the fourth gear pair 78 has the highest gearing compared to the first,second and third gear pairs 60, 66, 72, which results in the fourth gearpair 78 being connected when the lowest gear is engaged. The second gearpair 66 transfers, as does the fourth gear pair 78, torque between thesecond main shaft 36 and the countershaft 18, and could instead befitted out with the highest gearing, compared with the other gear pairs60, 72, 78, which is why in such an embodiment the second gear pair 66could be connected when the lowest gear is engaged.

When the countershaft 18 is made to rotate by the fourth cogwheel 82 onthe countershaft 18, the third cogwheel 76 on the countershaft 18 willalso rotate. Thus, the countershaft 18 operates the third cogwheel 76,which in turn operates the third pinion gear 74 on the first main shaft34. When the first main shaft 34 rotates, the first sun wheel 26 willalso rotate, and, depending on the rotational speed of the output shaft97 of the internal combustion engine 4 and thus on the rotational speedof the first planetary wheel carrier 50, it will cause the firstinternal ring gear 22 and the first rotor 24 of the first electricalmachine 14 to rotate. In this case it is possible to allow the firstelectrical machine 14 to operate as a generator, in order to supplypower to the energy storage device 46, and/or to supply power to thesecond electrical machine 16. It is also possible for the secondelectrical machine 16 to be operated as a generator. Alternatively, thefirst electrical machine 14 may emit a torque addition, by way of thecontrol device 48 controlling the first electrical machine 14 to providea driving torque.

In order to shift gears from the first to the second gear, the lockingbetween the second sun wheel 32 and the second planetary wheel carrier51 must cease, which is achieved by way of the first and/or the secondelectrical machine 14, 16 being controlled in such a way that torquebalance prevails in the second planetary gear 12. Subsequently, thesecond clutch device 58 is controlled in such a manner that itdisconnects the second sun wheel 32 and the second planetary wheelcarrier 51 from each other. The second planetary wheel carrier 51 andalso the second main shaft 36 may rotate freely, which entails that thesecond sun wheel 32, the second planetary wheel carrier 51 and thesecond main shaft 36 no longer operate the fourth pinion gear 80,arranged on the second main shaft 36. This assumes that the secondelectrical machine 16 does not operate the second ring gear 28. Thesecond gear is connected, by way of the control device 48 controllingthe internal combustion engine 4, in such a way that a synchronousrotational speed arises between the first planetary wheel carrier 50 andthe first sun wheel 26, in order to achieve a locking between the firstplanetary wheel carrier 50 and the first sun wheel 26. This is achievedby way of controlling the first clutch device 56 in such a way that thefirst planetary wheel carrier 50 and the first sun wheel 26 aremechanically connected with each other. Alternatively, the first clutchdevice 56 may be adapted as a slip brake or a multi-plate clutch, whichconnects, in a smooth way, the first sun wheel 26 with the firstplanetary wheel carrier 50. By synchronising the control of the internalcombustion engine 4 and the second and first electrical machine 14 and16, respectively, a soft and disruption-free transition from a first toa second gear may be carried out.

The first main shaft 34 now rotates, operated by the output shaft 97 ofthe internal combustion engine 4, and the first main shaft 34 nowoperates the third pinion gear 74. The first planetary wheel carrier 50thus operates the third pinion gear 74 via the first sun wheel 26 andthe first main shaft 34. Since the third cogwheel 76 is in engagementwith the third pinion gear 74 and is connected with the countershaft 18,the third cogwheel 76 will operate the countershaft 18, which in turnoperates the fifth cogwheel 92 on the countershaft 18. The fifthcogwheel 92 in turn operates the output shaft 20 of the gearbox 2 viathe sixth cogwheel 94, which is arranged on the output shaft 20 of thegearbox 2. The vehicle 1 is now operated with a second gear.

When the countershaft 18 is made to rotate by the third cogwheel 76, thefourth cogwheel 82 will also rotate. Thus, the countershaft 18 operatesthe fourth cogwheel 82, which in turn operates the fourth pinion gear 80on the second main shaft 36. When the second main shaft 36 rotates, thesecond planetary wheel carrier 51 will also rotate, and, depending onthe rotational speed of the output shaft 97 of the internal combustionengine 4, and thus on the rotational speed in the first planetary wheelcarrier 50, it will cause the second internal ring gear 28 and thesecond rotor 30 of the second electrical machine 16 to rotate. It isthus possible to allow the second electrical machine 16 to operate as agenerator, in order to supply power to the energy storage device 46,and/or to supply power to the first electrical machine 14. The secondelectrical machine 16 may also emit a torque addition, by way of thecontrol device 48 controlling the second electrical machine 16 towardsproviding a propulsion torque.

In order to shift from a second gear to a third gear, the fourthcogwheel 82 on the countershaft 18 must be disconnected from thecountershaft 18 with the fourth clutch element 90, so that the fourthcogwheel 82 may rotate freely in relation to the countershaft 18.Subsequently, the countershaft 18 is connected with the second cogwheel70 on the countershaft 18 via the second clutch element 86. In order toachieve a connection of the countershaft 18 and the second cogwheel 70on the countershaft 18, preferably the second electrical machine 16 iscontrolled in such a way that a synchronous rotational speed arisesbetween the countershaft 18 and the second cogwheel 70 on thecountershaft 18. A synchronous rotational speed may be determined by wayof measuring the rotational speed of the second rotor 30 in the secondelectrical machine 16, and by measuring the rotational speed of theoutput shaft 20. Thus, the rotational speed in the second main shaft 36and the rotational speed in the countershaft 18 may be determined by wayof given gear ratios. The rotational speed of the respective shafts 18,36 is controlled, and when a synchronous rotational speed has arisenbetween the countershaft 18 and the second cogwheel 70, the countershaft18 and the second cogwheel 70 are connected with the assistance of thesecond clutch element 86.

In order to complete the shift from a second gear to a third gear, thelocking between the first sun wheel 26 and the first planetary wheelcarrier 50 must cease, which is achieved by way of the first and/or thesecond electrical machine 14, 16 being controlled in such a way thattorque balance is achieved in the first planetary gear 10, followingwhich the first clutch device 56 is controlled in such a manner that itreleases the first sun wheel 26 and the first planetary wheel carrier 50from each other. Subsequently, the internal combustion engine 4 iscontrolled in such a way that a synchronous rotational speed arisesbetween the second sun wheel 32 and the second planetary wheel carrier51, so that the second clutch device 58 may be engaged, in order thus toconnect the second sun wheel 32 with the second planetary wheel carrier51, via the clutch sleeve 57. By synchronising the control of theinternal combustion engine 4 and the second and first electrical machine14 and 16, respectively, a soft and disruption-free transition from asecond to a third gear may be carried out.

The third cogwheel 76 is disconnected by controlling the firstelectrical machine 14 in such a way that a substantially zero torquestate arises between the countershaft 18 and the third cogwheel 76. Whena substantially zero torque state arises, the third cogwheel 76 isdisconnected from the countershaft 18 by controlling the third clutchelement 88 in such a way that it releases the third cogwheel 76 from thecountershaft 18. Subsequently, the first electrical machine 14 iscontrolled in such a way that a synchronous rotational speed arisesbetween the countershaft 18 and the first cogwheel 64. When asynchronous rotational speed arises, the first cogwheel 64 is connectedto the countershaft 18 by way of controlling the first clutch element 84in such a manner that it connects the first cogwheel 64 on thecountershaft 18. A synchronous rotational speed may be determined, sincethe rotational speed of the first rotor 24 in the first electricalmachine 14 is measured and the rotational speed of the output shaft 20is measured, following which the rotational speeds of the shafts 18, 34are controlled in such a way that a synchronous rotational speed arises.Thus, the rotational speed of the first main shaft 34 and the rotationalspeed of the countershaft 18 may be determined by way of given gearratios.

The second main shaft 36 now rotates with the same rotational speed asthe output shaft 97 of the internal combustion engine 4, and the secondmain shaft 36 now operates the second pinion gear 68 via the second mainshaft 36. Since the second cogwheel 70 is in engagement with the secondpinion gear 68 and is connected with the countershaft 18, the secondcogwheel 70 will operate the countershaft 18, which in turn operates thefifth cogwheel 92 on the countershaft 18. The fifth cogwheel 92 in turnoperates the output shaft 20 of the gearbox 2 via the sixth cogwheel 94,which is arranged on the output shaft 20 of the gearbox 2. The vehicle 1is now driven in a third gear.

When the countershaft 18 is made to rotate by the second cogwheel 70 onthe countershaft 18, the first cogwheel 64 on the countershaft 18 willalso rotate. Thus, the countershaft 18 operates the first cogwheel 64,which in turn operates the first pinion gear 62 on the first main shaft34. When the first main shaft 34 rotates, the first sun wheel 26 willalso rotate, and, depending on the rotational speed of the output shaft97 of the internal combustion engine 4, and thus on the rotational speedof the first planetary wheel carrier 50, it will cause the firstinternal ring gear 22 and the first rotor 24 of the second electricalmachine 16 to rotate. It is thus possible to allow the first electricalmachine 14 operate as a generator, in order to supply power to theenergy storage device 46, and/or to supply power to the secondelectrical machine 16. Alternatively, the first electrical machine 14may emit a torque addition, by way of the control device 48 controllingthe first electrical machine 14 towards providing a driving torque.

In order to complete the shift of gears from the third to the fourthgear, the locking between the second sun wheel 32 and the secondplanetary wheel carrier 51 must cease, which is achieved by way of thefirst and/or the second electrical machine 14, 16 being controlled insuch a way that torque balance prevails in the second planetary gear 12,following which the second clutch device 58 is controlled in such a waythat it releases the second sun wheel 32 and the second planetary wheelcarrier 51 from each other. A fourth gear is subsequently connected, byway of the control device 48 controlling the internal combustion engine4 in such a manner that a synchronous rotational speed arises betweenthe first planetary wheel carrier 50 and the first sun wheel 26, inorder to achieve a locking between the first planetary wheel carrier 50and the first sun wheel 26. This is achieved by way of controlling thefirst clutch device 56 in such a way that the first planetary wheelcarrier 50 and the first sun wheel 26 are mechanically connected witheach other. By synchronising the control of the internal combustionengine 4 and the second and first electrical machine 14 and 16 a softand disruption-free transition from a third to a fourth gear may becarried out.

The first main shaft 34 now rotates and is operated by the output shaft97 of the internal combustion engine 4, and the first main shaft 34 nowoperates the first pinion gear 62. The first planetary wheel carrier 50thus operates the first pinion gear 62 via the first sun wheel 26 andthe first main shaft 34. Since the first cogwheel 64 is in engagementwith the first pinion gear 62 and is connected with the countershaft 18,the first cogwheel 64 will operate the countershaft 18, which in turnoperates the fifth cogwheel 92 on the countershaft 18. The fifthcogwheel 92 in turn operates the output shaft 20 of the gearbox 2 viathe sixth cogwheel 94, which is arranged on the output shaft 20 of thegearbox 2. The vehicle 1 is now driven in a fourth gear.

When the countershaft 18 is made to rotate by the first cogwheel 64, thesecond cogwheel 70 will also rotate. Thus, the countershaft 18 operatesthe second cogwheel 70, which in turn operates the second pinion gear 68on the second main shaft 36. When the second main shaft 36 rotates, thesecond planetary wheel carrier 51 will also rotate, and, depending onthe rotational speed of the output shaft 97 of the internal combustionengine 4, and thus on the rotational speed in the first planetary wheelcarrier 50, it will cause the second internal ring gear 28 and thesecond rotor 30 of the second electrical machine 16 to rotate. It isthus possible to allow the second electrical machine 16 to operate as agenerator, in order to supply power to the energy storage device 46,and/or to supply power to the first electrical machine 14. The secondelectrical machine 16 may also emit a torque addition, by way of thecontrol device 48 controlling the second electrical machine 16 towardsproviding a propulsion torque.

In order to shift gears from a fourth gear to a fifth gear, the firstcogwheel 64 must be disengaged from the countershaft 18, so that thefourth gear is disengaged. This is achieved by way of controlling theinternal combustion engine 4 and the first electrical machine 14, insuch a way that the first cogwheel 64 is brought to a substantially zerotorque state in relation to the countershaft 18. When a substantiallyzero torque state has arisen, the first clutch element 84 is disengaged,so that the first cogwheel 64 is disconnected from the countershaft 18.

Subsequently, the rotational speed of the first main shaft 34 issynchronized with the rotational speed of the output shaft 20, followingwhich the clutch mechanism 96 is controlled in such a way that itconnects the first main shaft 34 with the output shaft 20.

Subsequently, the internal combustion engine 4 and the first electricalmachine 14 are controlled in such a way that the propulsion torqueoccurs via the first main shaft 34 and via the clutch mechanism 96, andfurther along to the output shaft 20. By reducing the torque from thesecond electrical machine 16, the fifth clutch element 93 may be broughtto a substantially zero torque state in relation to the countershaft 18.When a substantially zero torque state has arisen, the fifth clutchelement 93 is disengaged, so that the fifth cogwheel 92 of the fifthgear pair 21 is disconnected from the countershaft 18.

Subsequently, with the help of the second electrical machine 16, therotational speed of the countershaft 18 is synchronized with therotational speed of the third cogwheel 76, following which the thirdclutch element 88 is controlled in such a way that it connects the thirdcogwheel 76 with the countershaft 18. When this connection has beencompleted, the propulsion torque may be shared between the internalcombustion engine 4, the first electrical machine 14 and the secondelectrical machine 16. Subsequently, torque balance is created in thefirst planetary gear 10, following which the first clutch device 56disconnects the first planetary wheel carrier 50 and the first sun wheel26 from each other. Finally, the rotational speed of the secondplanetary wheel carrier 51 is synchronized with the second sun wheel 32,following which the second clutch device 58 connects the secondplanetary wheel carrier 51 and the second sun wheel 32 with each other.

The second main shaft 36 now rotates, operated by the output shaft 97 ofthe internal combustion engine 4, and the second main shaft 36 operatesthe second pinion gear 68. Since the second cogwheel 70 is in engagementwith the second pinion gear 68 and is connected with the countershaft 18via the second clutch element 86, the second cogwheel 70 will operatethe countershaft 18, which in turn operates the third cogwheel 76 on thecountershaft 18. The third cogwheel 76 in turn operates the first mainshaft 34 via the third pinion gear 74, and the output shaft 20 of thegearbox 2 is thus operated via the clutch mechanism 96, which connectsthe first main shaft 34 and the output shaft 20 of the gearbox 2. Thevehicle 1 is now driven in a fifth gear.

In order to shift gears from the fifth to the sixth gear, the lockingbetween the second sun wheel 32 and the second planetary wheel carrier51 must cease, which is achieved by way of the first and/or the secondelectrical machine 14, 16 being controlled in such a way that torquebalance is achieved in the second planetary gear 12, following which thesecond clutch device 58 is controlled in such a way that it releases thesecond sun wheel 32 and the second planetary wheel carrier 51 from eachother. A sixth gear is subsequently connected, by way of the controldevice 48 controlling the internal combustion engine 4, in such a waythat a synchronous rotational speed arises between the first planetarywheel carrier 50 and the first sun wheel 26, in order to achieve alocking between the first planetary wheel carrier 50 and the first sunwheel 26. This is achieved by way of controlling the first clutch device56 in such a way that the first planetary wheel carrier 50 and the firstsun wheel 26 are mechanically connected with each other. Bysynchronizing the control of the internal combustion engine 4 and thesecond and first electrical machine 14 and 16, respectively, a soft anddisruption-free transition from a fifth to a sixth gear may be carriedout.

The first main shaft 34 now rotates operated by the output shaft 97 ofthe internal combustion engine 4, whereat the first main shaft 34operates the output shaft 20 of the gearbox 2 via the clutch mechanism96, which connects the first main shaft 34 and the output shaft 20 ofthe gearbox 2. The vehicle 1 is now driven in a sixth gear.

In order to shift from a sixth to a seventh gear, the third cogwheel 76on the countershaft 18 must first be disconnected from the countershaft18 with the third clutch element 88, so that the third cogwheel 76 mayrotate freely in relation to the countershaft 18. Subsequently, thecountershaft 18 is connected with the first cogwheel 64 on thecountershaft 18 via the first clutch element 84. When the countershaft18 and the first cogwheel 64 on the countershaft 18 have a synchronousrotational speed, the first clutch element 84 is controlled in such away that the first cogwheel 64 and the countershaft 18 are connected.

In order to complete the shift from a sixth gear to a seventh gear, thelocking between the first sun wheel 26 and the first planetary wheelcarrier 50 must cease, which is achieved by way of the first and/or thesecond electrical machine 14, 16 being controlled in such a way thattorque balance is achieved in the first planetary gear 10, followingwhich the first clutch device 56 is controlled, in such a way that itreleases the first sun wheel 26 and the first planetary wheel carrier 50from each other. Subsequently, the internal combustion engine 4 iscontrolled in such a way that a synchronous rotational speed arisesbetween the second sun wheel 32 and the second planetary wheel carrier51, so that the second clutch device 58 may be engaged in order thus toconnect the second sun wheel 32 with the second planetary wheel carrier51, via the clutch sleeve 57. By synchronizing the control of theinternal combustion engine 4 and the second and first electrical machine14 and 16, respectively, a soft and disruption-free transition from asixth to a seventh gear may be carried out.

The second main shaft 36 now rotates with the same rotational speed asthe output shaft 97 of the internal combustion engine 4, and the secondmain shaft 36 operates the second pinion gear 68. Since the secondcogwheel 70 is in engagement with the second pinion gear 68 and isconnected with the countershaft 18, the second cogwheel 70 will operatethe countershaft 18, which in turn operates the first cogwheel 64 on thecountershaft 18. The first cogwheel 64 in turn operates the first mainshaft 34 via the first pinion gear 62, and the output shaft 20 of thegearbox 2 is thus operated via the clutch mechanism 96, which connectsthe first main shaft 34 and the output shaft 20 of the gearbox 2. Thevehicle 1 is now driven in a seventh gear.

According to the embodiment above, the gearbox 2 comprises pinion gears62, 68, 74, 80 and cogwheels 64, 70, 76, 82 arranged on the main shafts34, 36 and the countershaft 18, respectively, to transfer rotationalspeed and torque. However, it is possible to use another type oftransmission, such as chain and belt drives, to transfer rotationalspeed and torque in the gearbox 2.

The transmission device 19 has four gear pairs 60, 66, 72, 78 accordingto the example embodiment. However, the transmission device 19 maycomprise any number of gear pairs.

In order to achieve propulsion of the vehicle in a reverse direction, aspecial control of the hybrid powertrain is required, as described inFIG. 3a -3 c.

FIG. 3a shows a flow chart relating to a method to control a hybridpowertrain 3, in order to achieve reverse drive, wherein the hybridpowertrain 3 comprises an internal combustion engine 4; a gearbox (2)with an input shaft 8 and an output shaft 20; a first planetary gear 10,connected to the input shaft 8 and a first main shaft 34; a secondplanetary gear 12, connected to the first planetary gear 10 and a secondmain shaft 36; a first electrical machine 14, connected to the firstplanetary gear 10; a second electrical machine 16, connected to thesecond planetary gear 12; at least one gear pair 60, 72 connected withthe first main shaft 34 and the output shaft 20; and at least one gearpair 66, 78, connected with the second main shaft 36 and the outputshaft 20, wherein the internal combustion engine 4 is connected with thefirst planetary gear 10 via the input shaft 8. The hybrid powertrain 3is suitably adapted as described in FIG. 2. Method comprising the steps:

a) ensure that the moveable parts 22, 26, 50 of the first planetary gear10 are disconnected from each other, and/or that the moveable parts 28,32, 51 of the second planetary gear 12 are disconnected from each other;

b) ensuring that an output shaft 97 in the internal combustion engine 4is prevented from rotating; and

c) controlling the first electrical machine 14 and/or the secondelectrical machine 16, in such a way that a negative torque is achievedin the output shaft 20 via the first main shaft 34 and/or the secondmain shaft 36.

In cases where the vehicle is driven forward when the method describedherein is initiated, the moveable parts 22, 26, 50 of the firstplanetary gear 10 are disconnected by controlling the first and/or thesecond electrical machine 14, 16 in such a way that torque balance isachieved in the first planetary gear 10, whereat the first clutch device56 is shifted, so that the first planetary gear's 10 planetary wheelcarrier 50 and the first sun wheel 26 are disconnected from each other.In the same manner, the moveable parts 28, 32, 51 of the secondplanetary gear 12 are disconnected by way of controlling the firstand/or the second electrical machine 14, 16, in such a way that torquebalance is achieved in the second planetary gear 12, following which thesecond clutch device 58 is shifted, so that the planetary wheel carrier51 in the second planetary gear 12 and the second sun wheel 32 aredisconnected from each other.

Preferably, the method comprises, before step a), ensuring that theoutput shaft 20 is connected with the first and/or the second electricalmachine 14, 16. In this manner, torque transmission from the firstand/or the second electrical machine 14, 16 to the output shaft 20 isfacilitated.

The internal combustion engine's 4 output shaft 97 is connected with thefirst planetary wheel carrier 50 arranged in the first planetary gear10, and the step b) comprises ensuring that a locking device 102 islocked, so that the first planetary wheel carrier 50 is locked to thegear house 42 of the gearbox 4. Alternatively, step b) comprisescontrolling a braking element (not displayed), arranged in connectionwith the output shaft 97 of the internal combustion engine 4, so thatthe output shaft 97 of the internal combustion engine 4 is deceleratedto a standstill.

Preferably, step c) comprises controlling the first electrical machine14, in order to achieve a rotation of the first electrical machine 14 ina first direction, wherein the output shaft 20 is made to rotate in anopposite, second direction. The first direction is a positive direction.Suitably, the first electrical machine 14 is controlled in such a mannerthat it emits a positive torque, so that a rotation of the firstelectrical machine 14 in the first direction is achieved. The positivetorque from the first electrical machine 14 acts on the first sun wheel26, and thus on the first main shaft 34, so that they may rotate in asecond direction, opposite to the first direction. That is to say, thepositive torque from the first electrical machine 14 results in thefirst sun wheel 26 and thus the first main shaft 34 being able to obtaina negative rotational speed direction.

Preferably, step c) comprises control of the second electrical machine16, in order to achieve a rotation of the second electrical machine 16in a second direction, wherein the output shaft 20 is made to rotate inthe same, second direction. The second direction is a negativedirection. Suitably, the second electrical machine 16 is controlled insuch a manner that it emits a negative torque, so that the rotation ofthe second electrical machine 16 in the second direction is achieved.The negative torque from the second electrical machine 16 acts on thesecond planetary wheel carrier 51, and thus on a second main shaft 36connected with the second planetary wheel carrier 51, so that they mayrotate in the same, second direction. That is to say, the result of thenegative torque from the second electrical machine 16 is that the secondplanetary wheel carrier 51 and the second main shaft 36 may obtain anegative rotational speed direction.

FIG. 3b shows a flow chart relating to a method to control hybridpowertrain 3 according to FIG. 3a , wherein the negative torque in theoutput shaft 20 is achieved through the step—before the step a)

d) of ensuring that the first main shaft 34 connected with the firstplanetary gear 10 and the output shaft 20 are connected via a clutchmechanism 96.

This ensures that the output shaft 20 is connected with the first and/orthe second electrical machine 14, 16.

Suitably, step d) comprises achieving a synchronous rotational speedbetween the first main shaft 34 connected with the first planetary gear10 and the output shaft 20, following which the clutch mechanism 96 isshifted, so that it connects the first main shaft 34 and the outputshaft 20. Suitably, a synchronous rotational speed between the firstmain shaft 34 and the output shaft 20 is achieved via the internalcombustion engine 4 and/or the first electrical machine 14. Thesynchronous rotational speed between the first planetary gear 10 and thefirst main shaft 34 may be zero.

By connecting the first main shaft 34 and the output shaft 20, theoutput shaft 20 obtains the same rotational speed direction as the firstmain shaft 34. When the first electrical machine 14 is controlled inorder to achieve a negative torque in the output shaft 20, and thisresults in the first main shaft 34 obtaining a negative rotational speeddirection, the output shaft 20 obtains the same negative rotationalspeed direction. In this manner, a direct gear is achieved, whereat thefirst electrical machine 14 may achieve a negative torque in the outputshaft 20 without any connected gear pair.

Suitably, the method also comprises the step of, before step a):

f) ensuring that the at least one gear pair 66, 78 connected with thesecond main shaft is connected to the countershaft 18, and that thefifth gear pair 21 connected with the output shaft 20 is connected withthe countershaft 18.

This ensures that the output shaft 20 is connected with the first and/orthe second electric machine 14, 16.

The connection of a gear pair 66, 78 connected with the second mainshaft 36 is achieved in accordance with the description relating to FIG.2. The fifth gear pair 21 is suitably connected with the countershaft 18by way of controlling the internal combustion engine 4 and/or the firstelectrical machine 14, in such a manner that a synchronous rotationalspeed is achieved between the fifth gear pair 21 and the countershaft18, following which the fifth clutch element 93 is shifted, so that thefifth gear pair 21 is connected to the countershaft 18.

By connecting a gear pair 66, 78, connected with the second main shaft36, to the countershaft 18, the countershaft 18 will obtain a rotationalspeed direction opposite to the second main shaft 36. When the secondelectrical machine 16 is controlled in order to achieve a negativetorque in the output shaft 20, and this results in the second main shaft36 obtaining a negative rotational speed direction, the countershaft 18obtains a positive rotational speed direction. Since the countershaft 18is connected with the output shaft 20 via the fifth gear pair 21, apositive rotational speed direction in the countershaft 18 will entailthat the output shaft 20 may obtain a negative rotational speeddirection.

FIG. 3c shows a flow chart relating to a method to control hybridpowertrain 3 according to FIG. 3a , wherein the negative torque in theoutput shaft 20 is achieved through the step—before the step a)

e) ensuring that the at least one gear pair 60, 72 connected with thefirst main shaft 34 is connected to the countershaft 18, and that afifth gear pair 21 connected with the output shaft 20 is connected tothe countershaft 18.

This ensures that the output shaft 20 is connected with the first and/orthe second electrical machine 14, 16.

The connection of a gear pair 60, 72 connected with the first main shaft34 is achieved in accordance with the description relating to FIG. 2.The fifth gear pair 21 is suitably connected with the countershaft 18 byway of controlling the internal combustion engine 4 and/or the firstelectrical machine 14, in such a manner that a synchronous rotationalspeed is achieved between the fifth gear pair 21 and the countershaft18, following which the fifth clutch element 93 is shifted, so that thefifth gear pair 21 is connected to the countershaft 18.

Since a gear pair 60, 72 connected with the first main shaft 34 isconnected to the countershaft 18, a negative rotational speed directionin the first main shaft 34 means that the countershaft 18 obtains apositive rotational speed direction. Since the countershaft 18 isconnected with the output shaft 20 via the fifth gear pair 21, apositive rotational speed direction in the countershaft 18 will entailthat the output shaft 20 obtains a negative rotational speed direction.By controlling the first electrical machine 14 in such a way that itgenerates a positive torque, a negative rotational speed direction maythus be achieved in the output shaft 20 in a flexible manner.

Suitably, the method also comprises the step of, before step a):

f) ensuring that the at least one gear pair 66, 78 connected with thesecond main shaft 36 is connected with the countershaft 18, and that thefifth gear pair 21 connected with the output shaft 20 is connected withthe countershaft 18.

This ensures that the output shaft 20 is connected with the first and/orthe second electrical machine 14, 16.

The connection of a gear pair 66, 78 connected with the second planetarygear 12 is achieved in accordance with the description relating to FIG.2. The fifth gear pair 21 is suitably connected with the countershaft 18by way of controlling the internal combustion engine 4 and/or the firstelectrical machine 14, in such a manner that a synchronous rotationalspeed is achieved between the fifth gear pair 21 and the countershaft18, following which the fifth clutch element 93 is shifted, so that thefifth gear pair 21 is connected to the countershaft 18.

By connecting a gear pair 66, 78 connected with the second planetarygear 12 to the countershaft 18, the countershaft 18 obtains a rotationalspeed direction which is opposite to that of the second main shaft 36.When the second electrical machine 16 is controlled in order to achievea negative torque in the output shaft 20, and this results in the secondmain shaft 36 obtaining a negative rotational speed direction, thecountershaft 18 obtains a positive rotational speed direction. Since thecountershaft 18 is connected with the output shaft 20 via the fifth gearpair 21, a positive rotational speed direction in the countershaft 18will entail that the output shaft 20 may obtain a negative rotationalspeed direction.

According to the invention, a computer program P is provided, stored inthe control device 48 and/or the computer 53, which may compriseprocedures to control the hybrid powertrain 3 according to the presentinvention.

The program P may be stored in an executable manner, or in a compressedmanner, in a memory M and/or a read/write memory.

The invention also relates to a computer program product, comprisingprogram code stored in a medium readable by a computer, in order toperform the method steps specified above, when said program code isexecuted in the control device 48, or in another computer 53 connectedto the control device 48. Said program code may be stored in anon-volatile manner on said medium readable by a computer 53.

The components and features specified above may, within the framework ofthe invention, be combined between different embodiments specified.

1. A method to control a hybrid powertrain, in order to achieve reversedrive, wherein the hybrid powertrain comprises an internal combustionengine; a gearbox with an input shaft and an output shaft; a firstplanetary gear connected to the input shaft and a first main shaft; asecond planetary gear, connected to the first planetary gear and asecond main shaft; a first electrical machine connected to the firstplanetary gear; a second electrical machine connected to the secondplanetary gear; at least one gear pair, connected with the first mainshaft and the output shaft; and at least one gear pair, connected withthe second main shaft and the output shaft, wherein the internalcombustion engine is connected with the first planetary gear via theinput shaft, characterised by the steps said method comprising: a)ensuring that the moveable parts of the first planetary gear aredisconnected from each other, and/or that the moveable parts of thesecond planetary gear are disconnected from each other; b) ensuring thatan output shaft in the internal combustion engine is prevented fromrotating; and c) controlling the first electrical machine and/or thesecond electrical machine in such a way that a negative torque isachieved in the output shaft via the first main shaft and/or the secondmain shaft.
 2. A method according to claim 1, wherein the negativetorque in the output shaft is achieved by the step, before step a): d)ensuring that the first main shaft connected with the first planetarygear and the output shaft is connected via a clutch mechanism.
 3. Amethod according to claim 1, wherein the negative torque in the outputshaft is achieved by the step, before step a): e) ensuring that the atleast one gear pair, connected with the first main shaft is connected tothe countershaft and that a fifth gear pair, connected with the outputshaft is connected to the countershaft.
 4. A method according to claim1, wherein the output shaft the internal combustion engine is connectedwith a first planetary wheel carrier comprises ensuring that a lockingdevice is locked, so that the planetary wheel carrier is locked to thegear house of the gearbox.
 5. A method according to claim 1, wherein theat least one gear pair, which is connected with the first main shaftcomprises a first pinion gear and a cogwheel in engagement with eachother, which pinion gear is fixedly arranged with the first main shaftand which cogwheel is connectable and disconnectable arranged on acountershaft.
 6. A method according to claim 1, wherein the at least onegear pair, which is connected with the second main shaft comprises apinion gear and a cogwheel in engagement with each other, which piniongear is fixedly arranged with the second main shaft and which cogwheelis connectable and disconnectable arranged on the countershaft.
 7. Amethod according to claim 1, wherein step c) comprises controlling thefirst electrical machine in such a way that it rotates in a firstdirection, wherein the output shaft rotates in an opposite, seconddirection.
 8. A method according to claim 1, further comprising theadditional step, before step a): f) ensuring that the at least one gearpair connected with the second main shaft is connected to thecountershaft and that a fifth gear pair connected with the output shaftis connected to the countershaft.
 9. A method according to claim 1,wherein step c) comprises controlling the second electrical machine insuch a way that it rotates in a second direction, wherein the outputshaft rotates in the same, second direction.
 10. A vehicle with a hybridpowertrain, wherein the hybrid powertrain comprises an internalcombustion engine; a gearbox with an input shaft and an output shaft; afirst planetary gear connected to the input shaft and a first mainshaft; a second planetary gear connected to the first planetary gear anda second main shaft; a first electrical machine connected to the firstplanetary gear; a second electrical machine connected to the secondplanetary gear; at least one gear pair connected with the first mainshaft and the output shaft; and at least one gear pair connected withthe second main shaft and the output shaft, wherein the internalcombustion engine is connected with the first planetary gear via theinput shaft, wherein said hybrid powertrain is controlled to achievereverse drive by the method of: a) ensuring that the moveable parts ofthe first planetary gear are disconnected from each other, and/or thatthe moveable parts of the second planetary gear are disconnected fromeach other; b) ensuring that an output shaft in the internal combustionengine is prevented from rotating; and c) controlling the firstelectrical machine and/or the second electrical machine in such a waythat a negative torque is achieved in the output shaft via the firstmain shaft and/or the second main shaft.
 11. (canceled)
 12. (canceled)13. A vehicle according to claim 10, wherein the negative torque in theoutput shaft is achieved by the step, before step a): d) ensuring thatthe first main shaft connected with the first planetary gear and theoutput shaft is connected via a clutch mechanism.
 14. A vehicleaccording to claim 10, wherein the negative torque in the output shaftis achieved by the step, before step a): e) ensuring that the at leastone gear pair connected with the first main shaft is connected to thecountershaft and that a fifth gear pair connected with the output shaftis connected to the countershaft.
 15. A vehicle according to claim 10,wherein the output shaft of the internal combustion engine is connectedwith a first planetary wheel carrier arranged in the first planetarygear and that step b) comprises ensuring that a locking device islocked, so that the planetary wheel carrier is locked to the gear houseof the gearbox.
 16. A vehicle according to claim 10, wherein the atleast one gear pair, which is connected with the first main shaftcomprises a first pinion gear and a cogwheel in engagement with eachother, which pinion gear is fixedly arranged with the first main shaftand which cogwheel is connectable and disconnectable arranged on acountershaft.
 17. A computer program product comprising program codestored in a non-transitory computer-readable medium readable by acomputer, said computer program product used to control a hybridpowertrain in order to achieve reverse drive, wherein the hybridpowertrain comprises an internal combustion engine; a gearbox with aninput shaft and an output shaft; a first planetary gear connected to theinput shaft and a first main shaft; a second planetary gear connected tothe first planetary gear and a second main shaft; a first electricalmachine connected to the first planetary gear; a second electricalmachine connected to the second planetary gear; at least one gear pairconnected with the first main shaft and the output shaft; and at leastone gear pair connected with the second main shaft and the output shaft,wherein the internal combustion engine is connected with the firstplanetary gear via the input shaft, said computer program codecomprising computer instructions to cause one or more computerprocessors to perform the operations of: a) ensuring that the moveableparts of the first planetary gear are disconnected from each other,and/or that the moveable parts of the second planetary gear aredisconnected from each other; b) ensuring that an output shaft in theinternal combustion engine is prevented from rotating; and c)controlling the first electrical machine and/or the second electricalmachine in such a way that a negative torque is achieved in the outputshaft via the first main shaft and/or the second main shaft.
 18. Acomputer program product according to claim 17, wherein the negativetorque in the output shaft is achieved by further computer instructions,before computer instructions a) of: d) ensuring that the first mainshaft connected with the first planetary gear and the output shaft isconnected via a clutch mechanism.
 19. A computer program productaccording to claim 17, wherein the negative torque in the output shaftis achieved by further computer instructions, before computerinstructions a) of: e) ensuring that the at least one gear pairconnected with the first main shaft is connected to the countershaft andthat a fifth gear pair connected with the output shaft is connected tothe countershaft.
 20. A computer program product according to claim 17,wherein the output shaft of the internal combustion engine is connectedwith a first planetary wheel carrier arranged in the first planetarygear and that computer instructions b) comprises ensuring that a lockingdevice is locked, so that the planetary wheel carrier is locked to thegear house of the gearbox.
 21. A computer program product according toclaim 17, wherein the at least one gear pair, which is connected withthe first main shaft comprises a first pinion gear and a cogwheel inengagement with each other, which pinion gear is fixedly arranged withthe first main shaft and which cogwheel is connectable anddisconnectable arranged on a countershaft.